Newton’s Laws of Motion

Episode #7 of the course “Scientific laws and theories everyone should know”

Sir Isaac Newton uses three laws to describe the motion of enormous bodies and their interactions. While Newton’s laws now seem commonplace, a little over three hundred years ago, they were groundbreaking. Newton sits among the greatest scientific minds who ever lived, and his ideas became the basis for what we now know as physics. He founded calculus in addition to studying optics and astronomy.

In his theories, Newton made plain his consideration of colossal bodies by treating them as though they had no rotation or size. This treatment allowed him to ignore air resistance, friction, material properties, and temperature. This work also let him focus on phenomena that can only be demonstrated by mass, time, and length. As such, his three theories are not applicable to precisely explaining the behavior of significant objects that are rigid or deformable.  But in many cases, the laws still give suitable generalizations.

Newton’s three laws of motion define a foundational aspect of contemporary physics. Similar to other scientific laws, they are elegant and simple. His first movement law states that an object in motion stays in motion unless it is interfered with. For an egg that is rolled across the kitchen floor, the outside force may be the wall at the other end, or the person who picks the egg up from the floor.

Newton’s second motion law provides an association between the mass of an object (m) and the rate at which it speeds up (a) in the equation F = m × a. F denotes the force in Newton’s equation. Force doubles as a vector, as it retains a directional element. Because of the acceleration, that egg rolling across the floor keeps a particular direction that it is traveling; this direction is accounted for in the calculation of force.

The third motion law is significant and may be easily recognized: For every action there is an equal and opposite reaction. So for every amount of force given to an object or surface, that object will return that force with equal strength.

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